[xash]

OK, I took your instructions and tweaked the AddThis code to make the button blend in with the default vBulletin 3.7.x template, so it looks like an inbuilt feature. I've also added AddThis trackback code to track click analytics for links shared through the AddThis button, and I've set the mouseover pop-up delay to 350ms so that it doesn't annoy users by accidentally popping up the menu on hover.

Here's what it looks like on my forum (see the Share button, note how it looks like an inbuilt vBulletin button). It aligns perfectly in Opera, Chrome and Firefox:



And here's the code I used:

(make sure to substitute YOURADDTHISUSERNAME and YOURBOARDURL in the code below)

PHP Code:

<!-- AddThis Button BEGIN -->
<td class="vbmenu_control" id="addthis" nowrap="nowrap">
<div class="addthis_toolbox addthis_default_style">
<a href="http://www.addthis.com/bookmark.php?v=250&amp;username=YOURADDTHISUSERNAME" style="text-decoration:none;" class="addthis_button">Share <img src="http://YOURBOARDURL/images/misc/menu_open.gif" BORDER=0 /></a>
</div>
<script type="text/javascript">
var addthis_config = {
    data_track_clickback: true,
ui_delay: 350
}
</script>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#username=YOURADDTHISUSERNAME">
</script>
</td>
<!-- AddThis Button END -->